Find the linear function f(x) (where x is in miles and f(x) is in dollars)

Question

Suppose that a car rental agency charges a fixed amount per day plus an amount per mile for renting a car. Heidi rented a car one day and paid $101.50 for 190 miles. On another day she rented a car from the same agency and paid $154 for 340 miles. Find the linear function f(x) (where x is in miles and f(x) is in dollars) that the agency could use to determine its daily rental charges.

Answer 1

C = F + Mm

101.5 = F + M(190)

154 = F +M(340

subtract

52.5 = 150M

M = 52.5/150 = $0.35 = 35 cents per mile

F = 154 - 340(0.35) = 154-119= $35 per day

f(x) = 35 + 0.35x

f(x) = $35 daily charge plus 35 cents per mile